Date of Award


Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

First Advisor

Robert Bell


Purpose: The purpose of this study was to examine the associations between pre-operative weight loss, weight loss programs, and clinic attendance relative to the success of gastric bypass in class II and III obese patients. Background: The increasing number of obese children and adults in the United States poses an extensive social problem in the era of managed care. Notwithstanding the stigmatization associated with obesity, the considerable health implications along with the financial burden it imposes create a formidable adversary. Surgical procedures have proved to be superior to conservative and pharmacotherapeutic interventions in the morbidly obese. Despite the overall success of bariatric surgery, little information exists in the medical literature to predict patient outcome. Design/Methods: Our study was subdivided into three sections. First, we investigated the effects of patient adherence to pre-operative dietary and exercise recommendations. The change in body mass index (BMI) between initial consultation and pre-operative workup (average 6-8 weeks) was compared to change in BMI at the one year post operative period. The second study compared the maximum weight loss achieved by popularly used dietary programs to a physician monitored plan. On initial evaluation patients were asked to report information regarding weight loss attempts including program used and weight loss achieved. All individuals who had accurate records of their dieting attempts were included. We performed an ANOVA analysis and then Pearson and Spearman correlations between maximum pre-operative weight loss and one year post-operative weight loss. The last study conducted analyzed the association between clinic attendance and weight loss at yearly intervals. We also inquired about reasons for non-attendance and patient adherence in regards to vitamin supplementation, exercise regimen, and dietary intake. Results: From August 26, 2002 to July 31, 2006 a total of 404 laparoscopic Roux-en-y gastric bypass procedures were performed by Dr. Bell at Yale-New Haven Hospital. Of these patients 256 had one year post-operative weight data and were included in the first portion of the study. These subjects had an average pre-operative BMI 51.4 kg/m2 and ages which ranged from 17 to 64. At the one year post-intervention period, the mean percentage excess weight loss and percentage BMI loss were 62% and 34.5% respectively. Patients were categorized into two groups: those who had lost weight and those who had no change or gained weight after initial consultation. A multiple regression analysis and ANOVA showed no statistical difference between the two groups at the one year post operative period. The second portion of the study had 384 participants. A least squares analysis showed that physician monitored weight loss did not confer an advantage over popular commercial programs. In addition, linear regression analysis showed no correlation between maximum weight loss during dieting attempts and success at the one-year post-operative period measured by percentage of excess body weight loss. Lastly, in our evaluation of clinic attendance as a marker of success 283, 157, and 56 patients at the one, two, and three year interval respectively met inclusion criteria. A t-test at years one and two showed no statistically significant difference between those who attended clinic and those who did not.